<?php

/**
 * JPGraph v4.0.3
 */

namespace lemon\JpGraph\Plot;

use lemon\JpGraph\Image;
use lemon\JpGraph\Util;

/*
 * File:		JPGRAPH_CONTOUR.PHP
 * // Description: Contour plot
 * // Created:	 2009-03-08
 * // Ver:		 $Id: jpgraph_contour.php 1870 2009-09-29 04:24:18Z ljp $
 * //
 * // Copyright (c) Asial Corporation. All rights reserved.
 */
define('HORIZ_EDGE', 0);
define('VERT_EDGE', 1);

/**
 * This class encapsulates the core contour plot algorithm. It will find the path
 * of the specified isobars in the data matrix specified. It is assumed that the
 * data matrix models an equspaced X-Y mesh of datavalues corresponding to the Z
 * values.
 */
class Contour
{
	private $dataPoints   = [];
	private $nbrCols	  = 0;
	private $nbrRows	  = 0;
	private $horizEdges   = [];
	private $vertEdges	= [];
	private $isobarValues = [];
	private $stack;
	private $isobarCoord	= [];
	private $nbrIsobars	 = 10;
	private $isobarColors   = [];
	private $invert		 = true;
	private $highcontrast   = false;
	private $highcontrastbw = false;

	/**
	 * Create a new contour level "algorithm machine".
	 *
	 * @param $aMatrix	The values to find the contour from
	 * @param $aIsobars Mixed. If integer it determines the number of isobars to be used. The levels are determined
	 * automatically as equdistance between the min and max value of the matrice.
	 * If $aIsobars is an array then this is interpretated as an array of values to be used as isobars in the
	 * contour plot.
	 * @param null|mixed $aColors
	 *
	 * @return an instance of the contour algorithm
	 */
	public function __construct($aMatrix, $aIsobars = 10, $aColors = null)
	{
		$this->nbrRows	= safe_count($aMatrix);
		$this->nbrCols	= safe_count($aMatrix[0]);
		$this->dataPoints = $aMatrix;

		if (is_array($aIsobars)) {
			// use the isobar values supplied
			$this->nbrIsobars   = safe_count($aIsobars);
			$this->isobarValues = $aIsobars;
		} else {
			// Determine the isobar values automatically
			$this->nbrIsobars = $aIsobars;
			list($min, $max)  = $this->getMinMaxVal();
			$stepSize		 = ($max - $min) / $aIsobars;
			$isobar		   = $min + $stepSize / 2;
			for ($i = 0; $i < $aIsobars; ++$i) {
				$this->isobarValues[$i] = $isobar;
				$isobar += $stepSize;
			}
		}

		if ($aColors !== null && safe_count($aColors) > 0) {
			if (!is_array($aColors)) {
				Util\JpGraphError::RaiseL(28001);
				//'Third argument to Contour must be an array of colors.'
			}

			if (safe_count($aColors) != safe_count($this->isobarValues)) {
				Util\JpGraphError::RaiseL(28002);
				//'Number of colors must equal the number of isobar lines specified';
			}

			$this->isobarColors = $aColors;
		}
	}

	/**
	 * Flip the plot around the Y-coordinate. This has the same affect as flipping the input
	 * data matrice.
	 *
	 * @param $aFlg If true the the vertice in input data matrice position (0,0) corresponds to the top left
	 * corner of teh plot otherwise it will correspond to the bottom left corner (a horizontal flip)
	 */
	public function SetInvert($aFlg = true)
	{
		$this->invert = $aFlg;
	}

	/**
	 * Find the min and max values in the data matrice.
	 *
	 * @return array(min_value,max_value)
	 */
	public function getMinMaxVal()
	{
		$min = $this->dataPoints[0][0];
		$max = $this->dataPoints[0][0];
		for ($i = 0; $i < $this->nbrRows; ++$i) {
			if (($mi = min($this->dataPoints[$i])) < $min) {
				$min = $mi;
			}

			if (($ma = max($this->dataPoints[$i])) > $max) {
				$max = $ma;
			}
		}

		return [$min, $max];
	}

	/**
	 * Reset the two matrices that keeps track on where the isobars crosses the
	 * horizontal and vertical edges.
	 */
	public function resetEdgeMatrices()
	{
		for ($k = 0; $k < 2; ++$k) {
			for ($i = 0; $i <= $this->nbrRows; ++$i) {
				for ($j = 0; $j <= $this->nbrCols; ++$j) {
					$this->edges[$k][$i][$j] = false;
				}
			}
		}
	}

	/**
	 * Determine if the specified isobar crosses the horizontal edge specified by its row and column.
	 *
	 * @param $aRow Row index of edge to be checked
	 * @param $aCol Col index of edge to be checked
	 * @param $aIsobar Isobar value
	 *
	 * @return true if the isobar is crossing this edge
	 */
	public function isobarHCrossing($aRow, $aCol, $aIsobar)
	{
		if ($aCol >= $this->nbrCols - 1) {
			Util\JpGraphError::RaiseL(28003, $aCol);
			//'ContourPlot Internal Error: isobarHCrossing: Coloumn index too large (%d)'
		}
		if ($aRow >= $this->nbrRows) {
			Util\JpGraphError::RaiseL(28004, $aRow);
			//'ContourPlot Internal Error: isobarHCrossing: Row index too large (%d)'
		}

		$v1 = $this->dataPoints[$aRow][$aCol];
		$v2 = $this->dataPoints[$aRow][$aCol + 1];

		return ($aIsobar - $v1) * ($aIsobar - $v2) < 0;
	}

	/**
	 * Determine if the specified isobar crosses the vertical edge specified by its row and column.
	 *
	 * @param $aRow Row index of edge to be checked
	 * @param $aCol Col index of edge to be checked
	 * @param $aIsobar Isobar value
	 *
	 * @return true if the isobar is crossing this edge
	 */
	public function isobarVCrossing($aRow, $aCol, $aIsobar)
	{
		if ($aRow >= $this->nbrRows - 1) {
			Util\JpGraphError::RaiseL(28005, $aRow);
			//'isobarVCrossing: Row index too large
		}
		if ($aCol >= $this->nbrCols) {
			Util\JpGraphError::RaiseL(28006, $aCol);
			//'isobarVCrossing: Col index too large
		}

		$v1 = $this->dataPoints[$aRow][$aCol];
		$v2 = $this->dataPoints[$aRow + 1][$aCol];

		return ($aIsobar - $v1) * ($aIsobar - $v2) < 0;
	}

	/**
	 * Determine all edges, horizontal and vertical that the specified isobar crosses. The crossings
	 * are recorded in the two edge matrices.
	 *
	 * @param $aIsobar The value of the isobar to be checked
	 */
	public function determineIsobarEdgeCrossings($aIsobar)
	{
		$ib = $this->isobarValues[$aIsobar];

		for ($i = 0; $i < $this->nbrRows - 1; ++$i) {
			for ($j = 0; $j < $this->nbrCols - 1; ++$j) {
				$this->edges[HORIZ_EDGE][$i][$j] = $this->isobarHCrossing($i, $j, $ib);
				$this->edges[VERT_EDGE][$i][$j]  = $this->isobarVCrossing($i, $j, $ib);
			}
		}

		// We now have the bottom and rightmost edges unsearched
		for ($i = 0; $i < $this->nbrRows - 1; ++$i) {
			$this->edges[VERT_EDGE][$i][$j] = $this->isobarVCrossing($i, $this->nbrCols - 1, $ib);
		}
		for ($j = 0; $j < $this->nbrCols - 1; ++$j) {
			$this->edges[HORIZ_EDGE][$i][$j] = $this->isobarHCrossing($this->nbrRows - 1, $j, $ib);
		}
	}

	/**
	 * Return the normalized coordinates for the crossing of the specified edge with the specified
	 * isobar- The crossing is simpy detrmined with a linear interpolation between the two vertices
	 * on each side of the edge and the value of the isobar.
	 *
	 * @param $aRow Row of edge
	 * @param $aCol Column of edge
	 * @param $aEdgeDir Determine if this is a horizontal or vertical edge
	 * @param $ib The isobar value
	 * @param mixed $aIsobarVal
	 *
	 * @return unknown_type
	 */
	public function getCrossingCoord($aRow, $aCol, $aEdgeDir, $aIsobarVal)
	{
		// In order to avoid numerical problem when two vertices are very close
		// we have to check and avoid dividing by close to zero denumerator.
		if ($aEdgeDir == HORIZ_EDGE) {
			$d = abs($this->dataPoints[$aRow][$aCol] - $this->dataPoints[$aRow][$aCol + 1]);
			if ($d > 0.001) {
				$xcoord = $aCol + abs($aIsobarVal - $this->dataPoints[$aRow][$aCol]) / $d;
			} else {
				$xcoord = $aCol;
			}
			$ycoord = $aRow;
		} else {
			$d = abs($this->dataPoints[$aRow][$aCol] - $this->dataPoints[$aRow + 1][$aCol]);
			if ($d > 0.001) {
				$ycoord = $aRow + abs($aIsobarVal - $this->dataPoints[$aRow][$aCol]) / $d;
			} else {
				$ycoord = $aRow;
			}
			$xcoord = $aCol;
		}
		if ($this->invert) {
			$ycoord = $this->nbrRows - 1 - $ycoord;
		}

		return [$xcoord, $ycoord];
	}

	/**
	 * In order to avoid all kinds of unpleasent extra checks and complex boundary
	 * controls for the degenerated case where the contour levels exactly crosses
	 * one of the vertices we add a very small delta (0.1%) to the data point value.
	 * This has no visible affect but it makes the code sooooo much cleaner.
	 */
	public function adjustDataPointValues()
	{
		$ni = safe_count($this->isobarValues);
		for ($k = 0; $k < $ni; ++$k) {
			$ib = $this->isobarValues[$k];
			for ($row = 0; $row < $this->nbrRows - 1; ++$row) {
				for ($col = 0; $col < $this->nbrCols - 1; ++$col) {
					if (abs($this->dataPoints[$row][$col] - $ib) < 0.0001) {
						$this->dataPoints[$row][$col] += $this->dataPoints[$row][$col] * 0.001;
					}
				}
			}
		}
	}

	/**
	 * @param $aFlg
	 * @param $aBW
	 *
	 * @return unknown_type
	 */
	public function UseHighContrastColor($aFlg = true, $aBW = false)
	{
		$this->highcontrast   = $aFlg;
		$this->highcontrastbw = $aBW;
	}

	/**
	 * Calculate suitable colors for each defined isobar.
	 */
	public function CalculateColors()
	{
		if ($this->highcontrast) {
			if ($this->highcontrastbw) {
				for ($ib = 0; $ib < $this->nbrIsobars; ++$ib) {
					$this->isobarColors[$ib] = 'black';
				}
			} else {
				// Use only blue/red scale
				$step = round(255 / ($this->nbrIsobars - 1));
				for ($ib = 0; $ib < $this->nbrIsobars; ++$ib) {
					$this->isobarColors[$ib] = [$ib * $step, 50, 255 - $ib * $step];
				}
			}
		} else {
			$n	= $this->nbrIsobars;
			$v	= 0;
			$step = 1 / ($this->nbrIsobars - 1);
			for ($ib = 0; $ib < $this->nbrIsobars; ++$ib) {
				$this->isobarColors[$ib] = Image\RGB::GetSpectrum($v);
				$v += $step;
			}
		}
	}

	/**
	 * This is where the main work is done. For each isobar the crossing of the edges are determined
	 * and then each cell is analyzed to find the 0, 2 or 4 crossings. Then the normalized coordinate
	 * for the crossings are determined and pushed on to the isobar stack. When the method is finished
	 * the $isobarCoord will hold one arrayfor each isobar where all the line segments that makes
	 * up the contour plot are stored.
	 *
	 * @return array( $isobarCoord, $isobarValues, $isobarColors )
	 */
	public function getIsobars()
	{
		$this->adjustDataPointValues();

		for ($isobar = 0; $isobar < $this->nbrIsobars; ++$isobar) {
			$ib = $this->isobarValues[$isobar];
			$this->resetEdgeMatrices();
			$this->determineIsobarEdgeCrossings($isobar);
			$this->isobarCoord[$isobar] = [];

			$ncoord = 0;

			for ($row = 0; $row < $this->nbrRows - 1; ++$row) {
				for ($col = 0; $col < $this->nbrCols - 1; ++$col) {
					// Find out how many crossings around the edges
					$n = 0;
					if ($this->edges[HORIZ_EDGE][$row][$col]) {
						$neigh[$n++] = [$row, $col, HORIZ_EDGE];
					}

					if ($this->edges[HORIZ_EDGE][$row + 1][$col]) {
						$neigh[$n++] = [$row + 1, $col, HORIZ_EDGE];
					}

					if ($this->edges[VERT_EDGE][$row][$col]) {
						$neigh[$n++] = [$row, $col, VERT_EDGE];
					}

					if ($this->edges[VERT_EDGE][$row][$col + 1]) {
						$neigh[$n++] = [$row, $col + 1, VERT_EDGE];
					}

					if ($n == 2) {
						$n1									= 0;
						$n2									= 1;
						$this->isobarCoord[$isobar][$ncoord++] = [
							$this->getCrossingCoord($neigh[$n1][0], $neigh[$n1][1], $neigh[$n1][2], $ib),
							$this->getCrossingCoord($neigh[$n2][0], $neigh[$n2][1], $neigh[$n2][2], $ib), ];
					} elseif ($n == 4) {
						// We must determine how to connect the edges either northwest->southeast or
						// northeast->southwest. We do that by calculating the imaginary middle value of
						// the cell by averaging the for corners. This will compared with the value of the
						// top left corner will help determine the orientation of the ridge/creek
						$midval = ($this->dataPoints[$row][$col] + $this->dataPoints[$row][$col + 1] + $this->dataPoints[$row + 1][$col] + $this->dataPoints[$row + 1][$col + 1]) / 4;
						$v	  = $this->dataPoints[$row][$col];
						if ($midval == $ib) {
							// Orientation "+"
							$n1 = 0;
							$n2 = 1;
							$n3 = 2;
							$n4 = 3;
						} elseif (($midval > $ib && $v > $ib) || ($midval < $ib && $v < $ib)) {
							// Orientation of ridge/valley = "\"
							$n1 = 0;
							$n2 = 3;
							$n3 = 2;
							$n4 = 1;
						} elseif (($midval > $ib && $v < $ib) || ($midval < $ib && $v > $ib)) {
							// Orientation of ridge/valley = "/"
							$n1 = 0;
							$n2 = 2;
							$n3 = 3;
							$n4 = 1;
						}

						$this->isobarCoord[$isobar][$ncoord++] = [
							$this->getCrossingCoord($neigh[$n1][0], $neigh[$n1][1], $neigh[$n1][2], $ib),
							$this->getCrossingCoord($neigh[$n2][0], $neigh[$n2][1], $neigh[$n2][2], $ib), ];

						$this->isobarCoord[$isobar][$ncoord++] = [
							$this->getCrossingCoord($neigh[$n3][0], $neigh[$n3][1], $neigh[$n3][2], $ib),
							$this->getCrossingCoord($neigh[$n4][0], $neigh[$n4][1], $neigh[$n4][2], $ib), ];
					}
				}
			}
		}

		if (safe_count($this->isobarColors) == 0) {
			// No manually specified colors. Calculate them automatically.
			$this->CalculateColors();
		}

		return [$this->isobarCoord, $this->isobarValues, $this->isobarColors];
	}
}

// EOF
